Accueil > Actualités > Séminaires > Séminaire de Paolo Montagna


Titre : Coral geochemistry as a tool to understand biomineralization processes and climate variability
Nom du conférencier : Paolo Montagna
Son affiliation : ISMAR-CNR
Laboratoire organisateur : LOCEAN
Date et heure : 14-03-2017 11h00
Lieu : UPMC - 4 place Jussieu - Paris 5e - salle de réunion LOCEAN, tour 45/55, 4eme étage
Résumé :

Scleractinian   corals   can   provide   multi-century,   sub-annual resolution paleoceanographic records. They can be precisely dated by 230 Th/U technique and they systematically incorporate isotopic and chemical tracers that re!ect the environmental conditions of the ambient seawater.

On   the   other   hand,   the   chemical   and   isotopic   signals encoded   into   coral skeletons can  be  used   to   investigate  the   biomineralization   processes  and model   the   coral calci'cation   rate   in   the   future.   In   particular,   the boron isotopes extracted from the skeleton of zooxanthellate and azooxanthellate corals can e*ectively be used to quantify the internal pH and the response of calci'cation   to   ocean   acidi'cation   and  rising   seawater   temperature (McCulloch et al., 2012).

With the recent advances in analytical techniques, non-traditional stable and radiogenic isotopes can now be measured in relatively small coral portions and the results can be combined with established tracers in a unique multi-proxy approach.

I will present geochemical results from shallow- and deep-water corals from the Mediterranean Sea and the Southern Ocean. In particular, I will discuss the use  of Li/Mg  ratio and boron isotopes as reliable  proxies for seawater temperature   and   pH   as   well   as   coupled   U/Th   and  14 C for   water-mass ventilation,   with   examples   based   on long-lived   specimens   and   coral fragments from sediment cores.

McCulloch   M.,   Falter   J.,   Trotter   J.,   Montagna   P. (2012).  Coral   resilience   to ocean   acidification and global warming   through   pH   up-regulation.   Nature Climate Change, 2, 623-627.

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